The present invention relates to an apparatus and method for counting and more particularly to an electronic scale apparatus and method for counting the number of an unknown quantity of items.
In the prior art, there are known a variety of devices and techniques for counting an unknown quantity of articles, samples or items. These techniques have been used in manufacturing and other processes where there is a need to quickly count a number of items which are substantially similar to one another. One of the most common techniques used in lieu of manual counting employs a weighing device to first determine the total weight of a quantity of unknown items to be counted. This total weight is then divided by a representative weight of a single item to produce a quotient which may be rounded to the nearest integer and thereby represent the total number of items. This technique has been used for counting such items as currency, coupons and coins as well as a wide variety of other articles and goods in many different arts.
As will be apparent, the accuracy of the above technique is largely determined by the uniformity in the weight of each of the items in the unknown quantity to be counted. Naturally, if each of the items is of identical weight, the total weight divided by the unit weight of the item will produce a quotient which exactly equals the total number of items in the unknown quantity. Even when each of the items does not have an identical weight, however, fairly accurate indications of item count can still be obtained so long as the items each have a nominally uniform weight. In instances where the items are not of identical weight, the total weight divided by the weight of a representative item will result in a quotient which must be rounded to the nearest integer. The part of the quotient which is deleted to produce the rounding is representative of the error in the individual item weights. As will be apparent, the more that the weight of an individual item differs from the expected weight of the item, the more likely an error will be introduced into the weighing technique resulting in an inaccurate measurement of the total count of unknown items.
Even when the items have a nominally uniform weight, the chance of an error occurring in the measurement of the total count increases as the number of items increases. Thus, if only a small number of articles are weighed using prior art techniques, the possibility of error in the calculation may be small. However, if a large quantity of items are weighed, the possibility of error increases greatly and the accuracy of the count may be further compromised by resolution errors of the weighing system itself. The problem is further compounded when individual items vary more from the nominally uniform weight than a majority of the other items thereby introducing additional inaccuracies in the total count.
In order to overcome many of the above mentioned problems, a variety of techniques have been suggested to improve the accuracy of the item count. By way of example, there are known techniques which calculate a representative unit weight based on the weight of a known quantity of items. The unit weight is then recalculated in a successive number of steps to improve its accuracy as the quantity of items is increased. The total count is then determined by dividing the total weight of an unknown quantity of items by a revised average unit weight to produce a count indicative of the unknown number of items.
In still other instances, many systems use preset unit weights which are adjusted to compensate for a variety of factors which affect the individual weights of the items being counted. Thus, a representative unit weight may be calculated based upon the actual representative weight of an item under certain conditions, and then adjusted empirically when the conditions change. Again, such techniques may approximate the total count but are still likely to produce significant errors when counting large quantities of items.
Still another technique attempts to improve count accuracy by comparing the deviation of the quotient from the nearest integer. In this instance, when the computed quotient differs from the nearest whole number by more than a predetermined amount, the calculation is considered to be in error and the count ignored. In contrast, when the computed quotient is within a predetermined deviation from the nearest whole number, the count is considered to be accurate and rounding to the nearest integer may then be performed to produce the number indicative of the actual count. Again, when counting large quantities of items, the above technique is still likely to produce error resulting in an inaccurate count of the unknown quantity of items.
The above noted problems are particularly acute when utilizing electronic scales for counting currency in the form of bank notes, coins or the like. In particular, paper currency may be subject to a variety of conditions which contribute to significant variations in the weight of individual items. Dollar bills, for example, are widely used and may be torn, taped or otherwise mutilated thereby resulting in a weight which varies widely from the unit weight of a new dollar bill. In other instances, the individual weight of such bills may change drastically due to humidity or other atmospheric conditions. Contamination or soiling of the bills may further cause their weight to vary from the expected norm. In each instance, any attempt to weigh the bills and divide by a unit weight using prior known techniques is likely to result in a highly inaccurate reading of the total count and corresponding monetary value. Accordingly, for banks and other institutions requiring rapid and accurate counting of large quantities of notes and coins, such inaccuracies limit the acceptability and usefulness of the system under many circumstances.
In addition to the above limitations, the construction and operation of prior known systems has often required significant operator involvement to obtain the requisite counting. Thus, for example, operators must perform certain functions and sequences by providing inputs to the counting system for zeroing, adding successive quantities, changing the unit of measurement and other similar tasks before the final count can be obtained. Such operator intervention increases the likelihood of error or operator induced inaccuracies and increases the time necessary to complete the counting procedure. All of this results in reduced versatility and operator acceptance of the system.
Accordingly, the present invention has been developed to overcome the shortcomings of the above known and similar techniques and to provide a counting system and technique which improves accuracy and requires less operator intervention to produce a desired count.